1. Field
Methods and apparatuses consistent with exemplary embodiments relate to an electrocardiogram (ECG) sensing apparatus, and more particularly, to an ECG sensing apparatus which is built in clothing.
2. Description of the Related Art
Convergence between small-scale personal area technologies and health care equipments enable medical health care monitoring to be performed on a real time basis, and thus is expected as a high value-added field that can accomplish treatment and diagnosis.
The small-scale personal area technologies include radio frequency identification (RFID), ultra wide band (UWB), Bluetooth, Zigbee, wireless sensor network, etc., and these technologies have been developed to replace wires in various fields and provide convenience to users.
As such, recent wearable health care documents or products have announced a biosensor node of a miniaturized wearable type that can measure ECG and photoplethysmograph (PPG) signals on a real time basis and transmit bio-signals using a local area network, or various related products have been released.
The ECG signals, which are the most representative of bio-signals, make it possible to extract a variety of bio-information such as a heartbeat, a stress index, a breathing rate, arrhythmia, etc., and thus may be regarded as an indicator for providing information such as patient's heart condition or normal health condition.
A health care system of such a bio-based wearable type may cause a baseline noise due to breathing and may cause a muscle sound which is generated by an effect of peripherals or patient's motion.
In particular, motion artifacts may be caused by a change in the impedance of electrodes when a user wears the electrodes and walks, runs, or breathes. Such a noise may frequently appear when the ECG signals are recorded, and it is difficult to analyze the signals and thus it is difficult to diagnose and analyze exactly without removing the noise appropriately.
As a solution to prevent the baseline drift, the ECG may be monitored using a high pass filter of a high cutoff frequency. However, in this case, there is a problem that an effective ECG signal is distorted.
In recent years, an adaptive filter is used to remove the baseline drift noise overlapping the ECG or PPG signals. This filter may show good performance, but should use an objective reference signal to remove a noise signal overlapping original signals.
However, when a wrong reference signal is used as input, no noise signal is removed or the ECG signal may be distorted. Also, since the baseline noise should be removed using a certain reference signal as input every time that a noise signal overlaps the ECG signal, it is not easy to require mobility.